Continuous extrusion molding system for a weatherstrip

ABSTRACT

A continuous extrusion molding system for continuously extrusion molding a weather strip for an automobile includes a prickly gear, rotatable while pressed in contact with the weather strip being extruded, and disposed so as to be adjacent to a mouth piece of an extruder. Tiny holes having a depth reaching a core bar are defined preferably in a groove bottom of a U-like shape of a part of a slightly foamed solid rubber portion, in such a way as to be arranged in line along the longitudinal direction of the weather strip by use of the prickly gear.

This a division of Ser. No. 10/175,650, filed Jun. 20, 2002 now U.S.Pat. No. 6,686,020.

FIELD OF THE INVENTION

The invention relates to a weather strip for an automobile, comprising aslightly foamed solid rubber portion with a core bar embedded therein,and a continuous extrusion molding system for molding the same.

BACKGROUND OF THE INVENTION

On the basis of FIGS. 1 to 3, the related art is described hereinafterreferring to FIG. 5. When a weather strip 20 for an automobile,comprising a U-shaped trim 2 formed by embedding a core bar 4 in aslightly foamed solid rubber portion 3, is molded with a continuousextrusion molding system, a void 21 is prone to occur to a boundary partbetween the core bar 4 and the slightly foamed solid rubber portion 3due to a gas pocket formed. The reason for this is because a blowingagent contained in the slightly foamed solid rubber portion 3 isgasified as a result of being heated up by heat generated at the time ofextrusion molding with an extruder 11, and being heated up in avulcanizing furnace 15, and gas thus generated in part of the slightlyfoamed solid rubber portion 3, in close proximity to the core bar 4, isnot turned into bubbles, thereby gathering towards the core bar 4.

The void 21 tends to occur in a groove bottom 3 a of a U-like shape of apart of the slightly foamed solid rubber portion 3, substantiallyresembling the letter U, taking a tunnel form at times, or occurring ata number of successive places to a size in the order of 5 mm at othertimes. In case that the void 21 occurs to the slightly foamed solidrubber portion 3, the slightly foamed solid rubber portion 3 is peeledoff from the core bar 4, and will be in floating condition, causingdifficulty with conveying holding force of rubber to the core bar 4 whenpushing out the core bar 4 at the time of extrusion molding, that is, atthe time of breakout, so that the breakout of the core bar 4 can not beimplemented with ease. If the holding force is increased for thatreason, the surface of the slightly foamed solid rubber portion 3 isprone to be marred with holding marks, thereby aggravating externalappearance. In addition, presence of the void 21 interferes withattachment of the weather strip to a flange. Further, if the void 21occurs to an outer part 3 b of the solid rubber portion 3, this alsowill result in poor external appearance.

A thermoplastic elastomer comprises a rubber component (soft segment)for exhibiting elasticity, and a resin component (hard segment) forfluidizing at a high temperature and blocking plastic deformation atroom temperature, and the same is material that can be plasticized athigh temperature to be molded in the same way as a thermoplastic resin.A thermoplastic elastomer containing olefin-based components is calledan olefin thermoplastic elastomer (referred to as TPO).

Thus, with the weather strip 20 for the automobile, comprising theslightly foamed solid rubber portion 3 with the core bar 4 embeddedtherein, that is extrusion molded with the conventional continuousextrusion molding system, the void 21 is prone to occur to the boundarypart between the core bar 4 and the slightly foamed solid rubber portion3, and interferes with the attachment of the weather strip to theflange, resulting in poor external appearance. It is therefore an objectof the invention to provide a weather strip causing no such problems,and a continuous extrusion molding system for molding the same.

SUMMARY OF THE INVENTION

Referring to FIGS. 1, 2, 4, and 5, description is given hereinafter. Inthe first aspect of the invention, there is provided a weather strip 1for an automobile comprising a U-shaped trim 2 formed by embedding acore bar 4 in a slightly foamed solid rubber portion 3, foamed so as tohave a specific gravity of 0.8 to 1.2, wherein tiny holes 7 having adepth reaching the core bar 4 are defined in part of the slightly foamedsolid rubber portion 3, within the U-shaped trim 2, in such a way as tobe arranged in line along the longitudinal direction of the weatherstrip 1.

With the weather strip 1 for the automobile, having those features, tinyholes 7 having a depth reaching the core bar 4 are defined in a groovebottom of a U-like shape of part of the slightly foamed solid rubberportion, within the U-shaped trim, in such a way as to be arranged inline along the longitudinal direction of the weather strip 1.

Further, with the weather strip 1 for the automobile, having thosefeatures, tiny holes 7 having a depth reaching the core bar 4 may bedefined in an outer part 3 b of the slightly foamed solid rubber portion3, visible from outside, in such a way as to be arranged in line alongthe longitudinal direction of the weather strip 1, and the tiny holes 7are preferably sealed with a coating 8 formed of a thermoplasticelastomer or resin.

The invention provides in its second aspect a continuous extrusionmolding system 10 for continuously extrusion molding a weather strip 1for an automobile, comprising the U-shaped trim 2 formed by embedding acore bar 4 in a slightly foamed solid rubber portion 3, comprising aprickly gear 13, rotatable while pressed in contact with the weatherstrip 1 being extruded, and disposed so as to be adjacent to a mouthpiece 12 of an extruder 11, wherein tiny holes 7 having a depth reachingthe core bar 4 are defined in part of the slightly foamed solid rubberportion 3, within the U-shaped trim 2, in such a way as to be arrangedin line along the longitudinal direction of the weather strip 1 by useof the prickly gear 13.

Further, with the continuous extrusion molding system 10 having thosefeatures, tiny holes 7 may be sealed with a coating 8 formed of athermoplastic elastomer or resin, formed on the surface of the slightlyfoamed solid rubber portion 3, by use of a coating unit 16 after thetiny holes 7 having the depth reaching the core bar 4 are defined inpart of the slightly foamed solid rubber portion 3, within the U-shapedtrim 2, in such a way as to be arranged in line along the longitudinaldirection of the weather strip 1 by use of the prickly gear 13.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an automobile with a weather strip attachedthereto;

FIG. 2 is a cross-sectional view of the weather strip for theautomobile, taken on line Z—Z in FIG. 1;

FIG. 3 is a cross-sectional view of a conventional weather strip for anautomobile;

FIG. 4 is a cross-sectional view showing an embodiment of a weatherstrip for an automobile according to the invention, and a prickly gearand so forth of an embodiment of a continuous extrusion molding systemfor molding the weather strip for the automobile, according to theinvention;

FIG. 5 is a side view of the embodiment of the continuous extrusionmolding system for molding the weather strip for the automobile,according to the invention; and

FIG. 6 is a side view showing another embodiment of a continuousextrusion molding system for molding the weather strip for theautomobile, according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1, 2, and 4 show an embodiment of a weather strip 1 for anautomobile, according to the invention. The same comprises a U-shapedtrim 2 formed by embedding a core bar 4 in a slightly foamed solidrubber portion 3 foamed to have a specific gravity of 0.8 to 1.2, andthe slightly foamed solid rubber portion 3 has tiny holes 7 having adepth reaching the core bar 4, defined so as to be arranged in linealong the longitudinal direction of the weather strip 1, in order todischarge gas evolved inside the slightly foamed solid rubber portion 3at the time of extrusion molding and vulvanization into the air.

The weather strip 1 for the automobile, according to the embodiment, isattached to a flange 30 (or a flange at the rim of a door) at the rim ofan opening of an automobile body, and a hollow seal portion which is asponge rubber portion 5 for elastically contacting a door (or a bodypanel), and a lip portion 6 of the slightly foamed solid rubber portion3, for elastically contacting the body panel (or the door), are formedintegrally with the U-shaped trim 2, which is part of the slightlyfoamed solid rubber portion 3, fitted to the flange 30. In the figures,a door frame is denoted by reference numeral 31, and a door glass isdenoted by reference numeral 32.

With the present embodiment, the tiny holes 7 are defined in a groovebottom 3 a of a U-like shape of the U-shaped trim 2. As the groovebottom 3 a is a part normally most prone to occurrence of a void 21, gascan be discharged into the air by forming the tiny holes 7 therein,thereby preventing the void 21 from occurring.

Further, occurrence of the void 21 will not be limited to the partdescribed. Accordingly, the tiny holes 7 are formed as necessary in anyparts of the slightly foamed solid rubber portion 3, such as an outerpart 3 b of the U-shaped trim 2, both right side and left side partsthereof, and so forth, as targets for the formation of the tiny holes 7.

In the case where the tiny holes 7 are defined in the outer part 3 bvisible from outside, the tiny holes 7 are sealed with a coating 8formed of a thermoplastic elastomer or resin after gas is dischargedthrough the tiny holes 7, thereby enhancing agreeableness in appearance.

Furthermore, the slightly foamed solid rubber portion 3 of the weatherstrip has a specific gravity lowered to a suitable extent of a range of0.8 to 1.2 by foaming, and consequently, reduction in weight isimplemented without impairing mechanical strength required of theweather strip.

FIGS. 4 and 5 show an embodiment of a continuous extrusion moldingsystem 10 for the weather strip for the automobile, according to theinvention. The continuous extrusion molding system 10 is a system forcontinuously extrusion molding the weather strip 1 for the automobile,comprising the U-shaped trim 2 formed by embedding the core bar 4 in theslightly foamed solid rubber portion 3, and is provided with a pricklygear 13, rotatable while pressed in contact with the weather strip beingextruded, disposed so as to be adjacent to a mouth piece 12 of anextruder 11. The tiny holes 7 having the depth reaching the core bar 4are defined in the slightly foamed solid rubber portion 3 by use of theprickly gear 13 in such a way as to be arranged in line along thelongitudinal direction of the weather strip 1, thereby discharging gasevolved inside the slightly foamed solid rubber portion 3 in the air.

In the case where the tiny holes 7 are defined in the outer part 3 b ofthe U-like shape of a part of the slightly foamed solid rubber portion3, agreeableness in appearance can be enhanced if the tiny holes 7 arecovered with, and sealed by the coating 8 formed of a thermoplasticelastomer or resin after gas is discharged. In this case, for example,the tiny holes 7 may be defined so as to be arranged in line immediatelyafter the weather strip 1 is extruded out of the mouth piece 12, andthereafter, the tiny holes 7 may be continuously coated with resin byuse of a coating unit (another extruder, and so forth) 16 aftervulcanization in a vulcanizing furnace 15.

With the present embodiment, the prickly gear 13 is disposed at a spotabout 20 mm away from the mouth piece 12, continuously forming the tinyholes 7 in the groove bottom 3 a of the U-like shape of the U-shapedtrim 2 so as to be arranged in line along the longitudinal direction ofthe weather strip 1. Further, an embossing roll 14 is rotatably attachedto the mouth piece 12 so as to be rolled along on the outer face of theU-shaped trim 2 for continuously cutting an embossed pattern thereon.The weather strip 1 molded with the continuous extruding system 10 issent out to the vulcanizing furnace 15 to be heated therein forvulcanization.

Since the weather strip 1 molded with the continuous extruding system 10is provided with the tiny holes 7 having the depth reaching the core bar4, defined in the slightly foamed solid rubber portion 3, in theU-shaped trim 2, so as to be arranged in line along the longitudinaldirection of the weather strip 1, gas evolved inside the slightly foamedsolid rubber portion 3 due to heat at the time of extrusion molding andvulvanization can be discharged into the air. Accordingly, the void 21can be prevented from occurring.

The weather strip 1 passing through the vulcanizing furnace 15 may be attimes fitted to the flange 30 of the automobile body after two legs ofthe core bar 4 in a shape substantially resembling the letter U are bentso as to be parallel with each other as shown in FIG. 2.

In the first aspect of the invention, the weather strip 1 for theautomobile is provided with the tiny holes 7 having the depth reachingthe core bar 4, defined in the slightly foamed solid rubber portion 3,and consequently, gas evolved inside the slightly foamed solid rubberportion 3 at the time of extrusion molding and vulvanization can bedischarged into the air, thereby preventing the void 21 from occurringto the boundary part between the slightly foamed solid rubber portion 3and the core bar 4. Accordingly, it is possible to solve problems suchas difficulty with fitting the weather strip 1 for the automobile to theflange 30, and occurrence of poor external appearance.

With the weather strip 1 for the automobile, having those features, thetiny holes 7 are preferably sealed with a coating 8 formed of athermoplastic elastomer or resin, so that deterioration of agreeablenessin appearance does not occur.

The invention provides in its second aspect the continuous extrusionmolding system 10 for continuously extrusion molding the weather stripfor the automobile, comprising the prickly gear 13, rotatable whilepressed in contact with the weather strip 1 being extruded, and disposedso as to be adjacent to the mouth piece 12 of the extruder 11, wherein amultitude of the tiny holes 7, having the depth reaching the core bar 4,are defined in the slightly foamed solid rubber portion 3, so that gasevolved inside the slightly foamed solid rubber portion 3 can bedischarged into the air. Accordingly, occurrence of the void 21 can beprevented, thereby solving the problems such as difficulty with fittingthe weather strip 1 for the automobile to the flange 30, and occurrenceof poor external appearance.

Further, with the continuous extrusion molding system 10 having thosefeatures, wherein the tiny holes 7 formed in the outer part 3 b of theslightly foamed solid rubber portion 3 are sealed with a coating 8formed of a thermoplastic elastomer or resin by use of a coating unit16, deterioration of agreeableness in appearance of the weather strip 1as molded can be prevented.

1. A continuous extrusion molding system for continuously extrusionmolding a weather strip for an automobile, comprising a U-shaped trimformed by embedding a core bar in a slightly foamed solid rubberportion, said molding system comprising a prickly gear, rotatable whilepressed in contact with the weather strip being extruded, and disposedso as to be adjacent to a mouth piece of an extruder, wherein tiny holeshaving a depth reaching the core bar are defined in part of the slightlyfoamed solid rubber portion, within the U-shaped trim, in such a way asto be arranged in line along the longitudinal direction of the weatherstrip by use of the prickly gear, and a vulcanizing furnace forvulcanizing the U-shaped trim while the holes enable discharge of gasevolved inside the slightly foamed solid rubber portion.
 2. Thecontinuous extrusion molding system for continuously extrusion molding aweather strip for an automobile according to claim 1, and furthercomprising a coating unit for sealing the tiny holes with a coating of athermoplastic elastomer or resin, formed on the surface of the slightlyfoamed solid rubber portion.
 3. A continuous extrusion molding systemfor forming a weather strip for an automobile, comprising: an extruderhaving a mouth piece, said extruder outputting a slightly foamed solidrubber portion for embedding a core bar; a prickly gear disposedadjacent the mouth piece, the prickly gear rotatable when pressed incontact with the slightly foamed solid rubber portion being extruded forforming holes in a face of the slightly foamed solid rubber portion, theholes having a depth reaching the core bar; and a vulcanizing furnacefor receiving and vulcanizing the slightly foamed solid rubber portion,the holes enabling gas evolved inside the slightly foamed rubber portionto discharge therefrom while forming the slightly foamed rubber portionand the embedded core bar into a weather strip.
 4. The continuousextrusion molding system according to claim 3, further comprising acoating unit for coating and sealing the holes in the face of theslightly foamed solid rubber portion with a thermoplastic elastomer orresin.
 5. The continuous extrusion molding system according to claim 3,wherein said prickly gear comprises a rotatable wheel including aplurality of spaced radially outwardly projecting elongate elements,each said elongate element having a radially outwardly projecting tip.6. A continuous extrusion molding system for forming a weather strip foran automobile, comprising: means for providing a core bar; an extruderhaving a mouth piece, said extruder arranged to output a slightly foamedsolid rubber portion so that the core bar is embedded therein; a pricklygear disposed adjacent the mouth piece for rotating when pressed incontact with the slightly foamed solid rubber portion being extruded forforming holes in a face of the slightly foamed solid rubber portion; anda vulcanizing furnace for receiving and vulcanizing the slightly foamedsolid rubber portion, the holes enabling gas evolved inside the slightlyfoamed solid rubber portion to discharge during vulcanization, whileforming the weather strip.
 7. The continuous extrusion molding systemaccording to claim 6, including a coating unit for coating the weatherstrip with a thermoplastic elastomer or resin.
 8. The continuousextrusion molding system according to claim 7, including a bending meansfor forming the weather strip as a U-shaped weather strip.
 9. Thecontinuous extrusion molding system according to claim 8, including anembossing roll adjacent the exterior mouth piece and the prickly gearfor embossing the slightly foamed solid rubber portion output therefrom.10. The continuous extrusion molding system according to claim 8,wherein said prickly gear comprises a rotatable wheel including aplurality of spaced radially outwardly projecting elongate elements,each said elongate element having a radially outwardly projecting tipfor forming the holes.
 11. The continuous extrusion molding systemaccording to claim 6, wherein said prickly gear comprises a rotatablewheel including a plurality of spaced radially outwardly projectingelongate elements, each said elongate element having a radiallyoutwardly projecting tip for forming the holes.